In prior art Radio Frequency (RF) tuners, Automatic Gain Control (AGC) is often performed at the beginning of the RF signal path before the signal is fed to distortion-causing circuitry, such as amplifiers. For instance, tuners typically maintain an output signal power level at or below a certain reference value. The reference value is usually based on an assumption that the signal power level at any point in the signal path is unlikely to drive a component “to the rails” if the output signal is at or below the reference value. Attenuation is performed on the signal input when it is determined that the output signal power level is above the reference value.
In one prior art application, analog AGC is performed inside the first amplifier itself. However, this approach is prone to distortion, since the AGC is performed inside the amplifier. Another approach is to use a pin-diode attenuator in the signal path before the distortion-causing circuitry. However, pin-diode attenuators typically cannot be built on a semiconductor chip, such that in tuner-on-chip applications, the attenuation is performed off-chip.